This application is based on Japanese Patent Application No. 10-162151, filed Jun. 10, 1998, the contents of which are incorporated herein by reference.
The present invention relates to a computer system and its state control method and, more particularly, to a computer system which is removably dockable to an expansion unit and its state control method.
In recent years, various kinds of notebook type personal computers (note PCs) that are easy to carry and can be battery-driven have been developed. Such note PC can be docked to an expansion unit called a docking station or docking base, as needed, so as to expand its functions.
When a note PC is connected to the expansion unit and is used, the functions of the note PC can be easily expanded without impairing its portability.
Recently, an operating system having a function of automatically re-configuring the hardware environment of the system (e.g., a plug-and-play function) has been developed. When such operating system is used, by informing the operating system of docking of the note PC to the expansion unit, the system environment can be automatically changed to that in which the expansion unit can be used.
Recently, IBM Japan has released desktop PCs having functions called xe2x80x9cWake_on_LAN (WOL)xe2x80x9d for turning on desktop PCs under remote control from a server, and xe2x80x9cAlert_on_LAN (AOL)xe2x80x9d for automatically informing the server of abnormality of each desktop PC.
A typical remote management pattern using the WOL is as follows.
In an environment in which desktop PCs are set on the desks of individual employees as information tools in a company and are connected to a server via a LAN, when software programs installed in the respective desktop PCs are to be upgraded or when data are acquired from the respective desktop PCs, the IS department asks the employees to set their desktop PCs in a WOL enable state when they leave the company on a specific day. At midnight on that day, the server sends a special packet to the desktop PCs to automatically start up OFF or sleeping desktop PCs, thus upgrading the software program or acquiring data therefrom.
In case of a note PC, it is preferable that a LAN controller be accommodated not in the PC main body but in an expansion unit called a docking station or docking base, and that expansion unit be permanently connected to a LAN in an office. In this way, when the note PC is docked with the expansion unit in the office, it can be used as a desktop PC. On the other hand, when the user leaves the office, he or she can undock the note PC from the expansion unit and can carry it.
Furthermore, since the LAN controller consumes relatively large power, a power is supplied not from that note PC but from an AC adapter connected to the expansion unit to the LAN controller. That is, the use of the LAN controller must be permitted only when the AC adapter is connected. When the note PC suffers a low-battery state while the WOL function is enabled, remote control using WOL often cannot be normally executed.
However, when such arrangement that supplies a power only from the AC adapter connected to the expansion unit to the LAN controller is used, the LAN controller cannot operate unless the AC adapter is connected to that expansion unit. For this reason, a conventional docking informing function that informs the operating of docking of the note PC to the expansion unit at the time of docking can hardly correctly manage the state of the note PC.
More specifically, since the conventional function manages only two states, i.e., attachment (docking) and detachment (undocking) of the note PC to/from the expansion unit, even when a state change occurs owing to the presence/absence of the AC adapter, the OS cannot be informed of that state change. As a result, the use permission/inhibition control of the expansion unit cannot be done on the condition of the presence/absence of the AC adapter.
It is an object of the present invention to provide a computer system which can correctly manage the docking condition with an expansion unit and the use condition of a device in the expansion unit in consideration of connection/disconnection of an external power supply such as an AC adapter or the like, and its state control method.
In order to achieve the above object, according to the present invention, a computer system removably dockable to an expansion unit, comprises: a detector for detecting whether an external power supply is connected to disconnected to the expansion unit; and a controller for setting the computer system to a state in which the use of the expansion unit is permitted, when an occurrence of a connection event of the external power supply is detected by the detector while the computer system main body is being docked to the expansion unit.
In this computer system, connection of the external power supply to the expansion unit is used as the docking condition that permits the computer system use of the expansion unit. When an occurrence of the connection event of the external power supply is detected in a state wherein the computer system main body is being docked to the expansion unit, it is detected that the docking condition is satisfied, and the computer system is permitted to use the expansion unit; when an occurrence of a disconnection event of the external power supply is detected in that state, it is detected that the docking condition is not satisfied, and the computer system is inhibited from using the expansion unit.
Since a state change, i.e., whether or not the expansion unit can be used, is monitored using three states that take the presence/absence of the external power supply into consideration in addition to two states, i.e., docking/undocking to/from the expansion unit, even when the AC adapter is connected to the expansion unit after the computer system main body is docked to the expansion unit, the docking process can be normally executed, and the computer system can use the expansion unit.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.